From 1993 through
2002,
R. FORD DENISON taught crop ecology and conducted research at the
University of
California,
Davis, on topics ranging from
agricultural
sustainability to the evolution of
cooperation between microbes and plants. For most of this
time, he directed "the world's
youngest 100-year experiment" (LTRAS.ucdavis.edu),
tracking
the long-term trends that determine agricultural sustainability.
His work on symbiotic
nitrogen fixation, a possible
alternative to
nitrogen fertilizers, has led to a patent and publications
in
journals from Natureto Field Crops Research. One
recent paper, "Darwinian
Agriculture: When Can Humans Find Solutions Beyond the Reach of
Natural
Selection?" points out
some limitations both of agricultural biotechnology and of agriculture
that mimics natural ecosystems. He has been interviewed on National
Public Radio, Science Update (AAAS), and DeutschlandRadio and has been an
invited speaker at international meetings and at institutions
from
Japan's National
Agricultural Research Center to the Scripps Institute of
Oceanography. He was educated at Harvard, Evergreen, and
Cornell, where he earned a Ph.D. in Crop Science, with postdoctoral and
sabbatical research at UC Davis, UCLA, Queen's University (Ontario),
Welsh Plant Breeding Station (Aberystwyth), and University of
Minnesota. His
research
has
been supported by NSF, USDA, and California's
Agricultural Experiment Station. This web page was last updated
May 2005, when he moved to the University of Minnesota.

Research

How does evolution based on
"selfish genes" maintain cooperation? We are trying to answer
this question for
rhizobia,
symbiotic bacteria that infect legume plants like alfalfa or soybean
and (to varying extents) supply them with nitrogen. Fixing
nitrogen is costly for rhizobia, so why haven't rhizobia that supply
their plant hosts with nitrogen (indirectly benefiting competing
rhizobia infecting the same plant) been completely displaced by
"ineffective" rhizobia? Why are ineffective rhizobia common
enough to be a problem in some
soils but not others? This research
may lead to practical applications, such as legume
crops that selectively enrich the soil with the
most-beneficial
local strains of rhizobia. This research may also be relevant to other
cases where symbiosis
breaks
down, as in coral bleaching. As time allows, I also hope to
explore other applications of modern evolutionary theory, pursuing some
of the ideas in our paper on Darwinian Agriculture. Steve Kaffka
has replaced me as Director
of
LTRAS,
but I remain interested in scientific approaches to the problem of
long-term sustainability,
especially
that of agriculture. To pursue my research objectives, I have
often
had to develop new tools, including mechanistic
computer
models and noninvasive scientific instruments, such as the nodule
oximeter or a laser-scanner (at right)
to
measure green leaf area index in the field.

Denison, R.F., D.C. Bryant, and T.E.
Kearney. 2004. Crop
yields over
the
first
nine years of LTRAS, a long-term comparison of field crop systems in a
Mediterranean climate. Field
Crops Research
86:267-277.